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Questions and Answers
At what age do the first permanent molars typically erupt?
At what age do the first permanent molars typically erupt?
What is the size comparison of primary teeth pulp chambers to permanent teeth pulp chambers?
What is the size comparison of primary teeth pulp chambers to permanent teeth pulp chambers?
Which teeth erupt first according to typical developmental timelines?
Which teeth erupt first according to typical developmental timelines?
What is a common consequence of the premature loss of primary second molars?
What is a common consequence of the premature loss of primary second molars?
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What is the typical enamel thickness in primary teeth compared to permanent teeth?
What is the typical enamel thickness in primary teeth compared to permanent teeth?
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Which of the following is characteristic regarding the morphology of primary teeth?
Which of the following is characteristic regarding the morphology of primary teeth?
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When do the upper canines typically erupt?
When do the upper canines typically erupt?
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What is the typical order of eruption for the primary dentition?
What is the typical order of eruption for the primary dentition?
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What is a characteristic finding in eruption timing of primary teeth?
What is a characteristic finding in eruption timing of primary teeth?
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Which abnormality presents with a dental cyst associated with an unerupted tooth?
Which abnormality presents with a dental cyst associated with an unerupted tooth?
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What is the primary timing for the eruption of lower central incisors in months?
What is the primary timing for the eruption of lower central incisors in months?
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What age range corresponds to the eruption of the maxillary canine?
What age range corresponds to the eruption of the maxillary canine?
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Which characteristic of primary teeth enamel is correct?
Which characteristic of primary teeth enamel is correct?
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What is typically observed in the morphology of primary teeth compared to permanent teeth?
What is typically observed in the morphology of primary teeth compared to permanent teeth?
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Which eruption sequence indicates a common variation in timing for permanent dentition?
Which eruption sequence indicates a common variation in timing for permanent dentition?
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At what age does the completion of root development for primary incisors and molars typically take place?
At what age does the completion of root development for primary incisors and molars typically take place?
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What is a common consequence of premature loss of a primary second molar?
What is a common consequence of premature loss of a primary second molar?
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What features characterize the morphology of primary teeth pulp chambers?
What features characterize the morphology of primary teeth pulp chambers?
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When do upper lateral incisors typically erupt?
When do upper lateral incisors typically erupt?
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Study Notes
Primary Tooth Development
- Development begins at 7 weeks in utero.
- Eruption starts at 6 months of age
- Complete dentition at 2.5 years.
- Comprised of:
- 4 incisors
- 2 canines
- 4 molars
- Total of 20 teeth.
Primary Tooth Eruption
- Lower central incisors erupt at 6 months.
- All incisors erupt between 6-12 months.
- 1st molars erupt between 12-18 months.
- Canines and 2nd molars erupt between 18-36 months.
Primary Tooth Morphology
- Smaller than permanent teeth.
- Crowns more bulbous with pronounced labial/buccal cingulum
- More pronounced cervical margins, especially on the buccal side.
- Cusps more pointed.
- Narrower occlusal table.
- Broad, flat interproximal contact areas.
Primary Tooth Dentin
- Thicker dentin over pulpal wall at occlusal fossa.
Primary Tooth Pulp
- Larger pulp chambers.
- Higher pulpal horns, particularly in mesial horns.
- Longer, tortuous chambers.
- Shorter roots.
- Roots of primary incisors and canines are longer than the crown.
- Widely divergent roots.
- Multiple canals.
Primary Tooth Enamel
- Softer, more opaque, and more prominent aprismatic layer (making them appear whiter).
- Thinner enamel with more consistent depth (0.5-1mm) compared to permanent teeth (2.5mm).
- Primary teeth begin calcifying before birth, showing neonatal lines.
- Enamel rods at the cervix slope occlusally instead of gingivally.
- Molars have a constricted neck.
Dental Age
- Eruption of teeth.
- Resorption of the roots of primary teeth.
- Development of permanent teeth.
- Teeth typically emerge when 75% of their roots are completed.
- It takes 2-3 years for root completion after eruption.
Mixed Dentition
-
Age 6:
- Mandibular central incisor.
- Mandibular 1st molar.
- Maxillary 1st molar.
-
Age 7:
- Maxillary central incisors.
- Mandibular lateral incisors.
- Diastema may persist.
-
Age 8:
- Maxillary lateral incisors.
- 2-3 year delay before further eruption.
-
Age 9:
- Mandibular canine.
- 1st premolars
- ⅓ of root of mandibular canines and 1st premolars completed.
- Root development just starting on mandibular 2nd premolars.
- Root development on maxillary 1st premolars has begun and just starting for the 2nd premolar.
-
Age 10:
- Greater root resorption in primary canines and molars.
- Half the roots of the mandibular canine and 1st premolar completed.
- Nearly half the root of the maxillary 1st premolar complete.
- Significant root development of:
- Mandibular 2nd premolar.
- Maxillary canine.
- Maxillary 2nd premolar.
- Completion of roots of mandibular incisors.
- Roots of maxillary lateral incisors nearing completion.
-
Age 11:
- All roots of incisors and molars complete.
- Only primary teeth left:
- Maxillary canine.
- Maxillary 2nd molar.
- Mandibular 2nd molar.
-
Age 12:
- Remaining teeth:
- Maxillary canine.
- Maxillary 2nd premolar.
- Mandibular 2nd premolar.
- Early radiographic signs of 3rd molar formation
- Remaining teeth:
-
Age 13-15:
- 2nd molars.
- Root completion.
-
Age 18-21:
- 3rd molars
Normal Variations In Eruption
- Mandibular 2nd molars can erupt before premolars.
- Maxillary canines can erupt before premolars.
- If the maxillary canine erupts at the same time as the maxillary 1st premolar, the canine may be forced out labially.
- Asymmetries in eruption are expected, but should be within 6 months.
Exceptions to Normal Variations
- Primary 2nd molars have a greater mesio-distal dimension than the 2nd premolars and are retained in the arch until eruption at 10-12 years.
Consequences of Premature Tooth Loss
-
Crowding:
- Greater space loss in the upper arch.
- Loss of 2nd primary molars leads to greater loss of space than loss of the 1st molar.
- Very early loss of the 2nd molar can lead to loss of the 2nd premolar space.
- Mesial drift.
Primary Teeth
- Primary teeth begin developing at 7 weeks in utero.
- Primary teeth begin erupting at 6 months of age.
- All primary teeth erupt by 2.5 years of age.
- Primary dentition consists of 20 teeth, with 4 incisors, 2 canines, and 4 molars on each arch.
- Primary teeth are smaller than their permanent counterparts.
- The crowns of primary teeth are more bulbous, with a pronounced labial/buccal cingulum.
- Primary teeth have more pronounced cervical margins, especially on the buccal side.
- Primary teeth have more pointed cusps and a narrow occlusal table.
- Primary teeth have broad, flat interproximal contact areas.
- The dentine of primary teeth is thicker over the pulpal wall at the occlusal fossa.
- Primary teeth have larger pulp chambers, higher pulpal horns, and longer, tortuous chambers.
- The roots of primary teeth are shorter, and the roots of incisors and canines are longer compared to the crown.
- Primary tooth roots are widely divergent and have multiple canals.
- The enamel of primary teeth is softer, more opaque, and more prismatic.
- The enamel of primary teeth is thinner and more consistent in depth (0.5-1mm) compared to permanent teeth (2.5mm).
- Primary teeth start to calcify before birth and show neonatal lines.
- The enamel rods at the cervix of primary teeth slope occlusally instead of gingivally.
- Primary molars have a constricted neck.
Eruption Timing
- Lower central incisors erupt around 6 months.
- All incisors erupt by 6 – 12 months.
- First molars erupt between 12 – 18 months.
- Canines and second molars erupt between 18 – 36 months.
Common Abnormalities
- Natal teeth are teeth present at birth, usually lower central incisors.
- Eruption cysts, or dentigerous cysts, are fluid-filled sacs that develop around the crown of an erupting tooth.
Dental Age
- Dental age is determined by the eruption of teeth, the amount of root resorption, and the amount of development of permanent teeth.
- Teeth usually emerge when 75% of their roots are completed.
- Root completion takes 2-3 years after eruption.
- The eruption of primary teeth and the development of permanent teeth follow a specific timeline.
Eruption Timing and Development of Permanent Teeth
- By age 6, the mandibular central incisor, mandibular first molar, and maxillary first molar erupt.
- By age 7, the maxillary central incisors, mandibular lateral incisors, and the mandibular first premolars erupt.
- By age 8, the maxillary lateral incisors erupt, and there is typically a delay of 2-3 years before further eruption.
- By age 9, the mandibular canine erupts.
- By age 10, the roots of mandibular canines and first premolars are about one-third complete.
- By age 10, root development is just starting on the mandibular second premolar.
- By age 10, the root development of the maxillary first premolar has begun, and the development of the maxillary second premolar is just starting.
- By age 11, the roots of mandibular incisors are complete.
- By age 11, the roots of maxillary lateral incisors are nearly complete.
- By age 11, there is significant root development of the mandibular second premolars, maxillary canines, and maxillary second premolars.
- By age 12, all incisor and molar roots are complete.
- By age 12, the maxillary canines, the maxillary second molars, and the mandibular second molars are the only remaining primary teeth.
- By age 13-15, the roots of the second molars are forming.
- By age 18-21, third molars erupt.
Normal Variations
- The eruption of mandibular second molars may occur ahead of the premolars.
- The eruption of maxillary canines may occur ahead of the premolars, and if the maxillary canine erupts simultaneously with the maxillary first premolar, the canine may be forced labially.
- Asymmetries in eruption can occur, but they should be within 6 months.
Exceptions
- Primary second molars have a greater mesiodistal dimension than second premolars and are retained in the arch until the eruption of the permanent second premolars at 10-12 years of age.
Consequences of Premature Loss
- In cases of crowding, premature loss of primary teeth can lead to greater space loss, especially in the upper arch.
- The loss of second primary molars leads to greater space loss than first molars.
- Very early loss of a second molar can lead to the loss of the second premolar space.
- Premature loss of primary teeth can lead to mesial drift of teeth.
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Description
This quiz covers the development and eruption phases of primary teeth, including key milestones from 7 weeks in utero to complete dentition at 2.5 years. It also highlights the morphology and pulp characteristics of primary teeth. Test your knowledge on these essential aspects of pediatric dentistry!
